I’m putting together a 5L on the uber cheap. I found a used polysci chiller, a referbed 5L, and now I’m trying to figre out what pump I should get. Normally, I would do a Welch DryFast, but I was wondering if I could do it cheaper.
Anyone got some good suggestions for a pump on the cheap for this guy?
I just found a welch 2090b on ebay a few days ago for amazing cheap. That’s the SUPER SIZE version of the Welch Dryfast from a few years ago. I figure if it doesn’t work I get my money back and at around 150$ shipped for 88 L/Min @ 29" hg it will save me some vacuum oil!
I always prefer better equipment also. I was focusing on the word cheap. Dealing with oil sucks ill be getting a diaphragm soon too I hope. I use my harvest right freeze dryer as a cold trap.
I found it before from a vendor and saved it/changed the name and now I can only find it on this scribd thing. It shows how killer it is though compared to the other dryfast pumps and it does use the same numbering pattern (20 for chemical duty and the next two numbers are close to the L/Min). It is the only one that uses 3/8" instead of 1/4". I bet it was expensive.
I paid 100 to 200 shipped for my welch wob-l 2585b pumps used in good condition on eBay. the 2581 is an identical pump with lower cfm but pulls a deeper vacuum I haven’t seen those for cheap on eBay yet. Mind you I’m a cheap bastard so 200 dollars or more is high dollar for me ha
I use a wob-l 2522b for my 5l roto with out any issues. It only pulls to -25hg, but I read -13 to -15hg is only really needed. I scored 2 for $198.00 each off Ebay. I use them for Buchner filtration as well. No cold trap used
Is the Welch 2522B-01 chemical resistant? I’d like to be able to use it for ethanol recovery and DCVC with heptane, but I’m not sure if it will handle heptane very well. I was looking at the PILOT economy pump that Beaker has linked to, but the ability to pick up a used Welch for half the price of the PILOT is pretty enticing. Not if I’m constantly having to rebuild the damn thing or use cold traps, though. I’m guessing the Welch doesn’t have all of the teflon coatings?
So I have the 2090b up and running. It is amazing! No oil and according to my old gauge it pulls close to 30" HG. It is so fast it makes the air filter whistle. I’m still waiting for a few fittings to get it all proper but I’m using it to purge right now and it is easily 4x faster than using my old pump.
The thing is massive, though and I built a big stand and used 3/4" rubber washers but it walked the stand around I had to bunjee the stand down.